[QUOTE

the question is: if my bike was in a bike box like theirs were, would it count as regular luggage or someone would stop me and tell me to pay because they know its a bike inside?[/quote]

It's not so much about the bike inside,it's the fact that the box is over the maximum allowed size.The max.size on most airlines is between 60" and 65"(that means height+length+depth can't be more than X inches).Bike boxes are more like 36x48x10.